1. Field of the Invention
The present invention relates to high-voltage circuit breakers, and in particular to high-voltage circuit breakers including a closing resistor which, during closing of the breaker, is connected in parallel relationship with the main switching gap of the breaker by means of an auxiliary switching gap which closes before the main switching gap, and is disconnected, after the auxiliary switching gap closes, by opening the auxiliary switching gap before the main switching gap opens until the main switching gap is again closed; a movable spring-loaded contact pin, biased in the opening direction of the auxiliary switching gap; and a connecting rod which is linked to the auxiliary contact pin and is connected, hinged, to a rotatably supported crank drive of the drive unit of the circuit breaker.
2. Description of the Prior Art
In high-voltage circuit breakers of the foregoing type, which are described, for example, in German Pat. No. 21 08 915 (which corresponds to U.S. Pat. No. 3,763,340), the crank drive moves a crankpin which moves the connecting rod by means of a stop cam until the latter strikes a stationary tripping device and releases the connecting rod to permit a return movement. After the release, the crankpin moves in an elongated aperture which is disposed in the connecting rod and the length of which is matched to the length of the return travel of the auxiliary contact pin.
Siemens Publication "2-cycle SF.sub.6 Circuit Breaker 3AT5," Order No. B 122/1698-220, describes a high-voltage circuit breaker the crank of which consists of a drive lever connected to the connecting rod of the breaker, a spring-loaded dog member guided therein, and a drive disc connected to the drive shaft of the breaker, all of which are secured against mutual rotation. During closing of the breaker, the drive lever is rotated together with the drive disc due to the latched position of the dog member at the drive disc until a stationary stop disengages the dog member from the drive disc against the spring load, thus starting the return movement of the auxiliary contact pin, which is also spring-loaded.